SAN FRANCISCO— The federal agency that oversees offshore drilling is finally going to analyze the effects that intense, underwater seismic blasts have on whales and dolphins in the Gulf of Mexico. In a notice published today, the Bureau of Ocean Energy Management announced that it will evaluate the effects of seismic surveys used to detect oil under the seabed in an environmental impact statement.

“Whales and dolphins in the Gulf depend on sound for communication and finding food, but these blasts — sometimes as loud as an explosion — make it all but impossible,” said Miyoko Sakashita, oceans director at the Center for Biological Diversity. “I’m happy that the government is finally scrutinizing these underwater sound explosions, but it shouldn’t stop there. We simply have to do whatever’s needed to protect the Gulf’s sensitive wildlife.”

The agency and its predecessor, the Minerals Management Service, have for years allowed oil exploration using noisy seismic surveys without permits, in violation of the Marine Mammal Protection Act and the Endangered Species Act. A coalition of conservation groups sued the agency in 2010 for failing to look at the significant impacts of seismic surveys on whales and dolphins. That litigation (NRDC v. Salazar) remains active in the Eastern District Court of Louisiana.

“Seismic surveys have a vast environmental footprint — and in this case they’re harming the same populations of whales and dolphins already compromised by the Gulf spill,” said Michael Jasny, a senior policy analyst at the Natural Resources Defense Council. “It’s vital that the agencies take steps to evaluate and reduce the impacts.”

Seismic exploration surveys use arrays of high-powered air guns to search for oil and generate the loudest human sounds in the ocean short of explosives. The blasts, which can reach more than 250 decibels, can cause hearing loss in marine mammals, disturb essential behaviors such as feeding and breeding over vast distances, mask communications between individual whales and dolphins, and reduce catch rates of commercial fish.

“The epicenter of BP's drilling disaster is some of the most important hunting grounds for the Gulf's resident sperm whales, and dead dolphins are still washing up at elevated rates,” said Cynthia Sarthou, executive director of the Gulf Restoration Network. “It's critical that other impacts to Gulf marine mammals are scrutinized and minimized, so the government needs to carefully look at the impacts of seismic on these mammals and do everything possible to eliminate them.”

The environmental review of seismic surveys in the Gulf of Mexico is being prepared in anticipation of future permits for oil exploration surveys and also for regulations under the Marine Mammal Protection Act. The agency is seeking comments to guide its review of seismic surveys for 45 days.

The groups that sued over the failure to conduct an environmental analysis are the Center for Biological Diversity, Gulf Restoration Network, NRDC and Sierra Club.